Need honest advise - heart broken

So I am a grown women with a good job and have no problem being independent or take care of myself. However, I have for the last 20 months been in this fantastic relationship and I really mean fantastic. We fell madly in love very quickly and started talking about marriage and having kids. About 6 month ago he proposed and about one month ago we started TTC. Now to the hard very hard part. I just found out by catching him in an very small insignificant lie when we talked about all our fantatic memories from the start of our relationship that there was something not adding up. And then it all unraveled. Apparently in the first four months of our relationship (and yes it was very much a relationship - we told each other we loved one another, planned for or future, moving in and so on) he had sex with numerous other people. One he casually had sex with weekly..... He swears he stopped four months in and never touched another women (god knows what stopped him then) and the reason he lied/ didn't tell me was because he was afraid that the love of his life would leave him. Here are my questions. This man is/was truly the love of my life and now all of our relationship feels like a lie. All our wonderful memories in the beginning of the relationship gone ( we took our first vacation to Italy and it was magic we talked about getting engaged- the week we came back he texted this other women and they had sex!) All trust is broken. How do I proceed? For me this is the worst kind of cheating but he swears it was just then and he will never and has never since touched another women. I have moved out for now but i miss him so much. He continusly calls and texts me begging me to take him back and he will do anything to both prove that this was only then and never again. He continue to say it was 16 months ago and now he can't live without me. That this was the biggest mistake of his life and he therefore was petrified to tell me. Do you think it's possible to get over this and have a normal relationship? And if so what would you recommend we do more than see councillor. Or is this truly where I leave to not let him hurt me again? 20 months of total love (and it really was even when he was cheating - which scares me too) and now total despare - I am in so much pain.